Industries and municipal governments must comply with the environmental protection laws of both the federal government and the states in which they are located. In general, these laws require that any effluent or waste water must be free of unacceptable levels of undesired ions and substances.
The electroplating industry, for example, must remove chloride, chromium, cyanide and heavy metal ions such as nickel ions from waste water before it can be disposed. It is known that hexavalent chromium ions can be reduced to trivalent chromium ions and precipitated by the use of inorganic sulfur containing reducing compounds. It is also known that metal ions, such as nickel ions, can be removed from plating solutions with chelating agents. Methods also are known for dechlorinating plating solutions and reducing cyanide ions to cyanate ions which can be readily removed from the waste water.
At the present time, in order to remove a combination of undesired ions, such as chromium and/or chlorine and/or hypochlorite and/or cyanide and/or metal ions, it is necessary to analyze the ion content of the waste water to determine what agents to use or to treat the waste water stepwise with a series of different agents to insure the removal of all of the undesired ions that might be present.
There is obviously a need for a simple, inexpensive method of removing one or more undesired ions from an aqueous preparation. There also is a need for compositions for use in such a method.